SITE INFORMATION AND CORRESPONDENCE

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MEMORANDUM CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD - CENTRAL VALLEY REGION 3443 Routier Road, Suite A Phone: (916) 361-5600 Sacramento, CA 95827-3098 ATSS Phone: 8-495-5600 TO: Antonia Vorster FROM: Cori Condon Senior WRC Engineer Assoc. Eng. Geologist DATE: 19 August 1992 SIGNATURE: SUBJECT: SAMPLING AND ANALYSES PLAN, NAVAL COMMUNICATIONS STATION (NCS), STOCKTON I have reviewed the Sampling and Analyses Plan (SAP) submitted by the Department of the Navy, prepared by PRC Environmental on 26 June 1992. The SAP replaces the Interim Investigation Workplan submitted 8 August 1990 prepared by The Mark Group. The work proposed in the plan prepared by the Mark Group was not carried out and no additional investigation of the landfill , agricultural , and warehouse areas has been done since March 1989. PRC has proposed a site investigation including geophysical survey, surficial soil sampling, cone penetrometer testing (CPT) , soil sampling during CPT sounding, drilling and installing 33 additional monitoring wells (23 shallow and 10 intermediate depth) , well development, well sampling and water level measurements. Ground water samples will be collected quarterly and analyzed for priority pollutant constituents (volatile organics, semi-volatiles, metals, PCB's, and pesticides) and general minerals for four consecutive quarters. Analyses on the third and fourth quarter ground water samples will be modified based upon the analytical results from the first two quarters of ground water sampling. Analytical methods with lower detection limits should be used for these later quarterly sampling rounds. The goal of this phase of investigation is to verify the presence of contaminants reported in previous investigations, evaluate whether contaminants have been released at sites not previously investigated, more accurately locate sites in the landfill area, and obtain more data for evaluating potential migration of contaminants present in the ground water. I generally agree with the proposed work, and particularly support the development of a more complete data base through analysis of priority pollutants of all water samples. A time schedule 10r the oval-all CERCLA ii;vcStiy3tion needs tv be developed so that we know the direction of the Navy for at least the next two years. PRC has simplified the terminology of the NCS site study areas utilizing common usage and geography. The site has been broken into four basic study areas; the Landfill Area, the Warehouse Area, the Agricultural Area, and the Administrative Area. Review of the tasks proposed for each individual area follows. Landfill Area 1 . Formerly referred to as the Landfill and Burning Area, and PCB and Pesticide Sites. The Landfill Area comprises the western end of NCS Stockton and was the site of disposal operations from 1945 through 1979. The proposed future use of the Landfill Area is a wildlife refuge.